Improvement in apparatus for the increase of the speed of vessels



- I UNITED STATES PATENT. OFFICE.

ROBERT L. STEVENS, OF NEW YORK, N. Y., AND FRANCIS B. STEVENS, OFHOBOKEN, NEXV ERSEY.

IMPROVEMENT IN APPARATUS FOR THE INCREASE OF THE SPEED OFVESSELS.

Specification forming part of Letters Patent No; 5,644, dated J une 20,1848.

To all whom it may concern.-

Be it known that we, ROBERT L. SrEvENs,

of the city, county, and State of New York,

and FRANCIS 13.. STEVENS, of Hoboken, in the county of Hudson, in theState of New Jersey, have invented certain Improvements in ApplyingMeans and Apparatus to Vessels and Ships to Increase or Improve TheirSpeed; and we do hereby declare that the following is a full and exactdescription thereof.

It has long been known that the resistance that hinders or impedes themotion of vessels through the water arises from three causes Viz., thedisplacement of the water by the vessel, the suction (as it is termed)at the stern, produced by the motion of the vessel from the water, and,lastly, the friction produced by the immersed surface of the vesselpassing through the water. WVe have not noticed the inertia of the massto be propelled, as that. when once overcome is no longer a resistanceand the propelling machinery is always constructed with aview to actregularly and keep up the acquired momentum It has also long been knownthat the resistance caused by the displacement, as also. that caused bythe suction, could be reduced by making the Vessel sharper and ofgreater length in proportion to the breadth, so that the water as thevessel moves through it could be displaced by the bow more easily andfill up at the stern more gradually. The friction produced by theimmersed surface of the vessel in passing through the water hasfrequently been looked upon as too trifling to be considered an elementin calculating the resistance to the motion of vessels, and hence butfew efforts have been made to reduce or modify a resistance generallysupposed tov be much less than it actually is. Although the experimentsmade in 1796, 800., by Colonel Beaufoy upon the subject of theresistance of fluids have been considered as the basis of all otherinvestigations upon this subject, still his experiments upon the subjectof friction have not generally attracted that attention which theydeserve. The amc"nt of the friction of water (against a surface ofwoodplaned smooth and painted) for each square foot of surface immersedin the water and the general law of its increase at differ-- entVelocities were given by him at velocities from two to ten miles perhour. Theseexperiments on friction have been corroborated and continuedby another series carefully conducted by us on the Delaware and RaritanCanal, in New Jersey, with various substances and qualities of surfaceand at speeds of from one mile per hour to upward of forty. By theseexperiments we have proved that the resistance due to friction increasesas the squares of the velocities, and we have found that in the sharpeststeamboats of the presentda-ythatwhich hasbeenfrequentlydeemed tooinconsiderable to enter into a calculation is the largest element ofresistance.

In vessels where the length is small in proportion to the breadth, andwhere the angles of the bow and stern are obtuse, the resistance causedby thefriction of thewater against the sides and bottom of the vessel isvery small compared with the resistance caused by the displacement andthe suction; but in vessels where the length is very great in proportion to the breadth, and where the angles of the bow and stern areexceedingly sharp, the resistance caused by the friction of the water isgreater than the resistance caused by the displacement and the suction.WVe have found by actual experiment that in a vessel two hundred andtwenty feet long, sixteen feet wide at the water-line, molded veryround, or,as it is technically termed, much out up, drawing three feetof water, and the angle of the bow six degrees, more than three quartersof the resistance to the motion of a this vessel was due to the frictionof its immersed surface passing through the water. The means commonlyused to diminish this friction have been to render that part of thesurface of the vessel as smooth and even as possible; but we have becomesatisfied by ourexperiments,madewithvarioussubstances and on varioussurfaces, that even on the most highly-polished surfaces there is muchvfriction, much more than is generally supposed. lVe have been particularin stating the existence of this friction, its magnitude, and the law ofits increase, as it is the object of the principal part of our inventionfor improving the speed of vessels to diminish this friction, and thiswe do by the interposition of a stratum of atmospheric air between theimmersed surface of the vessel and the water,

which we find greatly reduces the resistance arising from this friction.The air is to be applied and supplied continuously to the bottom of thevessel while it is in motion, and over the whole or as large a portionof the immersed surface as possible, and to be introduced by bellows orother blowing apparatus through pipes,channel-ways, or other conductorsleading to apertures made in the sides and bottoms of vessels, or bymeans of pipes or other conductors running over the sides and bows ofvessels and terminating in apertures or orifices distributed over theimmersed surface of vessels.

It has been a maxim among naval architects and constructors that toprevent as much as possible the friction of the immersed surface ofvessels against the water, it (the surface of vessels) must be madesmooth but to interpose air between the surface of the Vessel and thewater with the view to reduce friction we depart from this maxim, and indeparting from itewe make over the entire immersed surface to besupplied with air certain irregularities, consisting of projections andrecesses, which produce two useful eifectsviz., first, they make theinterposition of the air more perfect by distributing it equally overthe entire surface and by retaining it more perfectly and for a longertime than could otherwise be done, and, second, they produce by awell-known physical law a suction in the aper tures tending to supplythe air, by which less pressure is required to supply the air tov beinterposed between the surface of the vessel and the water. The mostefiectual way of making the projections and recesses is to put them onin manner somewhat resembling the scales of a fish or the shingles onthe roof of a house-that is, a series of inclined planes forming aslight angle with the plane of the vessels surface, and arranged in thedirection of the length of the vessel, so that the summit of all theplanes will be toward the stern, that when in motion the water shall bythe direction of the motion pass from the tip of one scale to the tip ofthe next succeeding one, the air on the inclined surface of the recessesform ed-by the series of theplanes or scales having the effect toprevent the water from being forced by the pressure of the column intothe recesses. The air will thus be sheltered in a measure in theserecesses, and the vessel will be in contact with the water only at ornear the tips of the scales, and will thus pass with a stratum of airinterposed between its surface and the est part of each recess andconducted there from'pipes, channel-ways, or other conductors by holesmade in the vessel or by branch pipes passing through the holes, so thatthe air may issue at the deepest part of the re cesses and pass alongandspread over the entire surface of the planes; but itisnot necessary, toproduce a beneficial effect, that there should be an aperture in eachrecess as the air introduced in the recesses at the bow is carried fromthence under the bottom of the vessel toward the stern and forcedup bythe surrounding water into the recesses not otherwise supplied. We wouldobserve that when there is no air in the recesses We have always foundthese projections and recesses detrimental, causing more resistance tothe motion of the vessel than a plane sur-.

face Would do. The recesses formed between the summits of the series ofplanes should be divided into cells by longitudinal partitions toprevent the escape of the air at the sides. The use of projecting partsand recesses for the purpose above specified constitutes the second partof our invention.

The air applied as above described, besides reducing the friction, willhave the effect to diminish the suction at the stern of .the vessel. WVehave found by experiment that if apertures are made at the stern largein size and placed closely together and communieating with theatmosphere by tubes the pressure of the atmosphere through these tubeswill diminish the suction of the Vessel in its passage through thewater. We place these apertures as closely together as possible Withoutweakening too much the structure of the vessel or reducing too much thebuoyancy at the stern. The tubes or conductors leading to the atmospheremust terminate at such distance from the water as may be deemedrequisite to prevent the water from overflowing them.- The use of theseapertures at the stern to diminish the suction constitutes the thirdpart of our invention.

We will now proceed to describe by reference to drawings how the surfaceof a vessel ,is to be constructed with the view to the application ofour invention.

1n the accompanying drawings, Figure 1 is a face view of a portion ofthe surface of avessel on our improved plan; Fig. 2, a horizontalsection taken at the line XX of Fig. 1, and Fig. 3 a vertical sectiontaken at the line Z Z of v the same figure.

On the ordinary planking aof a vessel constructed in any desired manner,which plank vessel. These wedge likc projections, which we term thescales," because of their resemblance to the scales of a lish, overlapone anof each scale, and thespaccs between the sumi'nits constitute thereccs named inthe preceding part of this spec fication, and thoserecesses are lurther div de into cells ny longitudinal partitions toprevent the escape of the air at the sides. Holes fare made in theplanking of the vessel, to which pipes g are fitted leading to mainpipes h or channelwa vs orothernmin conductors for the supply of air,and the holes], one or more for each cell, should be made under theprojecting or after partof each scale, so that the air in issuingfromthese holes may dill'use itself and cover the entire surface of eachcell. instead of making the scales to overlap, their after ends maybeperpendieularto the. plane oi'thevessci, as shown in section, l ig. 4,or instead of this the recesses may be made of double and reversedinclined planes 5 1., as shown in section, Fig. 5, or therecesscs maybeformed between ribs 7 Z, the edges oi which may bi.- rounded oil, asshown in section liig. 3. lo.

these various modifications the holes ior the supply of air should bemade in the most d pressed part of the recesses.

At Fig. l will be seen the side elevation ol. an entire vessel with thescales applied. This is .re 'n'oseuled as being propelled bypaddlewheels; but othermodes of propelling maybe substituterfl, such asscrews, sails,-&-e.

\Ve have used the inclined planes of various dimensions and have foundthe proper inclination to be of more inipii rtauce than the length. \Yehave used them three inc-hes long with an inclination of one intwenty-five, and eight feet long with an inclination of one in ninety,with a beneficial eilect. 'lhcsc projectionsand recesses can be forrnc'?art of the solid material of the vessel or made separate and attached.thereto. If it were judged inexpedientto make the apertures through thebottom of a vessel, tubes could be run over the sidesand introduced inthe intervals between the planking and the project-ions or scales, orthe vessel may be built with two thicknesses of planking and the airintroduced into an interval left between them, this space beingseparated into divisions b v ribs running from the bow toward the stern.

The air, as above mentioned, can be applied to a vessels bottom withoutthe intervention ot' these projections; but, excepting at very lowVelocities and where the nature of the construction mag: render itnecessary, we prefer the application of it by means of projections andrecesses; l-ut when applied without the rcees Cswe should recommrznlthat the apertures be covered \vii h plates and the air madeto issuet'"oin under the after part of these plates,or that a rib orscalobcplaced in front of the aperture or apertures to reduce the pressurerequired to force out the air. in re spent. to the qnant-it vol airrequired.wehave at the peed of .ii't'tfeen flillc-- per hour used oneand a half cubic feet-per minute for each .apiare foot ot. the immersed"surfacecf the ot-her,leavinga space I? under theafter part 3 vessel andhave found it to produce a boneticial etfect,;and at a speed of twei'rty-eight miles per hour we have used five cubic feet ol air perminute for each square 'foot with beneficial effect, the scales beingsixteen inches long, and having an inclination of one in sixty. We havegiven no directions as to the blowing apparatus b: v which the air mustbe supplied, as this would of course vary according to circumstances,the subject of forcing air under different pressures being wellunderstood. (faremusl. be taken that. the air be delivered at differentpressures to the orifi es that are at different depths or perpeir(licular distauces from the surface of the water, so that the greaterportion of the air shall not escape from a few of the apertures.

in respect to the suction. produced by the recesses, we would remarkthat at a speed of twelve miles per hour with scales one foot long,having an inclination of one in twentyi'ive, the water was all drawn outof a lube six inches'deep, and this suction increased ith theveloeity,so that'at a speed of twentyl'our miles per hour the water wasdrawn out oi? a tube thirty inches deep, and we Found that at a speed oithirty miles an hour suilieientair was drawn under the sides and bottomof a vessel drawing one-foot of water to produce a beneficial effectwithout the intervention of blowing apparatus.

If it should be judged inadvisable vfrom the want of sutlicient power toforce the air, or from other causes to supply the air, over the wholeimmersed surface of the vessel, the projections and recesses could beapplied to a portion only of the surtface. This method of diminishingthe friction applicable to all vessels; but it is more peculiarlyadapted to vessels where the length is great in proportion to thebreadth, where. the-angles of the.

bow and stern are sharp, and where the draft of water is light, so thata sui'licient supply of air can be 'readily obtaineifl.

lly the method above (lesr'ribcd the friction of the water against thewhole nnnersed sun face and the suction at the stern is dimiuished, butthe resistanci-i caused by the dis placement at the bow remains a fixedumb lily, the way of reducing which is by giving the vessel greaterlength in proportion to the .h and by reducing the angle of the Thisangle we recommend to be as sharp as the construction of the vessel andthe purposes for which it is intended will allow.

it will be obvious that if any of the pen nianeutly-elast-icgnses besubstituted in whole or in part for atmospheric air the same elli'cctwill be nrin'luced.

We are aware that it has been proposed to surround the bottom of avessel with ledges,

making lln bottom like an inverted l'migand,

lo inlrmluec air, under a pressure, into this box for the purpose ofraising it to decrease the draft of water; that air has also been forcedunder. the water from a vessel to act as a propelling agent. We are alsoawarethat a patent was granted in England, in the'year 1818 to ThomasCochraneand Alexander Gal-. loway which included among other matters thegetting rid of the'gasesevolyed from the combustion in theboiler-furnacesof a steamer, or, as they'say, to allow 'suchgases toescape for dissipation byblowing them ,under water, but withoutintention to diminish friction and withoutany description of means bywhich it could produce the efli'ect; but

What-we claim as our invention, and desire to secure by Letters Patent,isa I l 1. Applying air to theimmersed surface of a vessel in motion, inmanner substantially as described, and thus interpose (by acontinuous orintermittent supply) a stratum of air between the immersed surfaceorportions thereof-of 'the'vessel and the water for the purpose ofreducing the friction of the water,

as described. We do not claim this application to propel the vessel,butto be used in-connection and combination with paddle-wheels,screws,-sai1s, or other propelling agent.

2,- T-herecesses on theiinmersedsurface of the Lyessel formed by thescales or otherirregulari- I ties, as described; or anythingsubstantially the same, when combined with thesupplylut, of air, for thepurpose of distributing the air and for retaining it moreperfectlyand-for a longer time between the surface of the Ve -m and thewater; but it are be understood 8112; we do not claim the'serefcessesindependently of their use andco-nnectiou with the use of air to reducefriction; H

3. The plates over the air-apertures or the scales or ribs in front,substantially as described, to reduce the pressure required for thedischarge of the air; but this we claim only when air is used as meansof reducing friction.

4. The apertures made in the stern of a ves- 'sel, communicating withthe atmosphere by pipes or other conductors, for the purpose 0tdiminishing that resistance produced by the motion of the'vessel fromthe water, commonly We do not 1 claim the use of these apertures,excepting in I called the suction at "the stern.

